This application relates to valves, especially valves for plumbing fixtures, fittings and water supply systems and installations for washing, showering, bathing and the like employing such plumbing fixtures and fittings. The invention has particular, but not exclusive, application to a mixer valve, especially a thermostatic mixer valve and, more particularly, to an electronically controlled thermostatic mixer valve. The invention also relates to a flow control valve and to applications of such flow control valve in plumbing fixtures and fittings and parts thereof including, for example, a mixer valve.
A mixer valve receives a fluid flow from at least two sources and provides an output comprising a mix or blend of the sources. Typically, mixer valves are used to control water flow in plumbing fixtures and fittings. In such fixtures and fittings, the mixer valve commonly receives a first input from a cold water supply and a second input from a hot water supply. The mixer valve includes controls that act to control in what proportions the hot and cold supplies are mixed. Thus, the mixer valve mixes the hot and cold supplies in accordance with the setting of its controls to achieve a desired water outlet temperature.
Manually operable thermostatic mixer valves typically include a valve member that is manually adjustable to blend the hot and cold supplies in the correct proportion to set a desired water outlet temperature and a thermostat responsive to the water outlet temperature to adjust the position of the valve member to maintain constant the selected water outlet temperature. The known manually operable thermostatic mixer valves may also provide control of the water outlet flow rate.
An example of such manually operable thermostatic mixer valves is shown in FIGS. 12 and 13. The mixer valve 101 is designed for mounting on a wall or partition 102 within a shower enclosure and has elbow members 103, 104 either side of a waisted body 105. The elbows 103, 104 are connected to incoming supplies 106, 107 of hot and cold water entering the enclosure through the wall 102.
The body 105 houses a valve mechanism including a valve member that is axially movable between hot and cold seats to control the relative proportions of hot and cold water admitted to a mixing chamber. The valve member is manually adjusted to set the desired outlet water temperature by a rotatable temperature control knob 110 at the front of the body 105.
The mixing chamber communicates with an outlet 108 in the body. The outlet 108 is shown arranged on the underside of the body 105 when the valve 101 is installed on the wall 102 for connection to a flexible hose that 109 delivers water to a handset. In other arrangements, the outlet may be arranged on the top of the body 105 when the valve 101 is installed on the wall 102 for connection to a rigid riser pipe that delivers water to a fixed overhead shower.
The valve mechanism includes a thermostat responsive to the water temperature in the mixing chamber to adjust the position of the valve member to maintain constant the selected water temperature. The valve further includes a rotatable flow control knob 111 mounted concentric with the temperature control knob 110 to control and regulate the flow of water from off to fully open.
Such known valves 101 are relatively large (the inlets centers are typically spaced 150 mm (6 inches) apart) and are often made of metal and therefore relatively heavy and expensive to manufacture.
Electronically controlled thermostatic mixer valves typically utilize motors to control the movement of a valve member to blend the hot and cold supplies in the correct proportion to set a desired water outlet temperature and a temperature sensor responsive to the water outlet temperature to provide a signal to control circuitry to operate the motor to adjust the position of the valve member to maintain constant the selected water outlet temperature.
An example of such electronically operable thermostatic mixer valves is shown in FIGS. 14 and a mixer unit incorporating the mixer valve is shown in FIG. 15. The mixer valve 201 has a body 202 with inlets 203, 204 for connection to supplies of hot and cold water and an outlet 205. The body 202 houses a valve mechanism including a valve spool 206 having two parts 206a, 206b provided with interlocking castellations that form a series of slotted ports 207.
The inlets 203, 204 open to inlet chambers that surround the spool 206 and the valve spool 206 is axially movable between a first end position in which the ports 207 communicate with the inlet chamber connected to the cold water supply corresponding to full cold and a second end position in which the ports 207 communicate with the inlet chamber connected to the hot water supply corresponding to full hot. Between the end positions, the ports 207 communicate with both inlet chambers and, adjusting the axial position of the spool 206 between the end positions adjusts the relative proportions of hot and cold water flowing to the outlet 205 and thus the water outlet temperature.
The spool 206 is axially adjustable under the control of a stepper motor 208 that is coupled to the spool 206 by a drive mechanism including a drive rod 209. The stepper motor 208 is controlled by an electronic controller 210 (FIG. 15) arranged to receive signals from a user interface (not shown) for selecting the desired water outlet temperature and from a temperature sensor (not shown) mounted in the outlet 205 to adjust the position of the spool 206 to achieve and maintain the desired outlet water temperature.
Such known electronic mixer valves 201 are relatively large and only control the outlet water temperature not the flow rate. Consequently a separate electronically operable flow control valve 211 is provided with associated controls to start/stop water flow and control the flow rate. The flow control valve 211 has an inlet 212 connected to the outlet 205 of the mixer valve 201. A valve member 213 engages a valve seat 214 to prevent flow of water from the inlet 212 to an outlet 215 in the closed position of the valve.
The valve member 213 is urged away from the valve seat 214 to open the flow control valve 211 when a solenoid 217 is energized and opening movement of the valve member 213 is controlled by a stepper motor 216 via a drive rod 218 to control the flow rate of water delivered to the outlet 215. The stepper motor 216 is controlled by the electronic controller 210 that receives signals from the user interface for selecting the desired flow rate of the outlet water and from a flow rate sensor mounted in the outlet to adjust the position of the valve member 213 to achieve and maintain the desired outlet water flow rate.
The mixer valve 201 and separate flow control valve 211 are typically combined in a single unit 219 within a housing 220 for connection to the electrical supply for the stepper motors. The large size of the units 219 renders them unsuitable for mounting in a shower enclosure. As a result, they are usually mounted remote from the shower enclosure, for example in the ceiling above the shower enclosure with the outlet 215 supplying connecting pipework to deliver outlet water to an overhead shower, a handset or other spray device within the shower enclosure and with a wired or wireless connection from the user interface located in the shower enclosure to the electronic controls for the mixer valve and flow control valve.
Due to the size and complexity of many parts of the mixer valve and flow control valve that form the water way and come into contact with the water, such parts are made of plastics materials to facilitate manufacture and reduce the weight of the units. The use of plastics materials however gives rise to a health risk from the presence of harmful micro-organisms in the water supply, especially bacteria and in particular legionella bacteria. The bacteria readily form a bio-film on surfaces of the waterway in contact with the water that are made of plastics material and the growth of bacteria forming the bio-film is promoted in the warm water present in the waterways, especially immediately after use while the water remaining in the valve is still warm and before it has cooled down. The large surface area of the waterways in the known electronically controlled mixer valves therefore presents a particular problem for effective control of bacteria to reduce the risk of users being infected by bacteria in the fine droplets of water present in the shower area when showering and which can be readily inhaled.
It is known to periodically flush the waterways with hot water for a pre-determined period of time, typically at least 65° C. for at least 10 minutes, to kill bacteria present on the surface of the waterways. However, if the water used is not hot enough or is not present for a sufficient period of time the bacteria can survive and continue to grow. Also flushing with hot water may not remove bacteria present on the surface of the waterway in trapped areas of the waterway that are not flushed by the hot water. This can be a further problem affecting the efficient removal of bacteria in complex waterways made of plastics materials.
Hence a need exists for improved valves for plumbing fixtures, fittings and water supply systems and installations for washing, showering, bathing and the like employing such plumbing fixtures and fittings.